I. Field of the Invention
The present invention relates generally to balancers and, more particularly, to an automatic balancer for a rotating body.
II. Description of the Prior Art
There have been several previously known automatic balancers for rotating bodies, such as a rotating shaft. Two such devices are disclosed and described by A. Deakin in his U.S. Pat. Nos. 3,282,127 and 3,410,154. These previously known Deakin shaft balancers briefly comprise a housing having an outer rim and an inwardly spaced cage which floats within the housing. A number of ball members are disposed in the annular channel formed between the cage and the housing rim which assume a circumferential position around the channel necessary to correct an imbalance of the rotating body. The cage, or fingers as they are also known in the trade, are freely floatable within the housing and this permits the ball members to move around the annular channel to a circumferential position necessary to correct an unbalanced condition.
With the free floating cage of the previously known Deakin balancers, it has been found that the cage is subject to shift at high rotation speeds. An unbalanced condition results when the cage shifts so that the operational stability speed of the Deakin balancers is limited. A still further disadvantage of the floating cage construction shown by the previously known Deakin balancers is that after prolonged rotation, even at low rotational speeds, the balancer undergoes brief periods of instability from the shifting cage. Although the previously known Deakin balancers immediately correct for the momentary unbalance of the rotating shaft, elimination of this momentary and periodic instability of the balancer would be highly desirable.
Another previously known shaft balancer is disclosed by Rogers in his U.S. Letters Pat. No. 3,109,321. The Rogers patent discloses a shaft balancer in which ball members assume a circumferential position around a housing necessary to correct the unbalanced condition. The Rogers balancers utilize radially movable finger elements and an elastromeric retainer band. A primary disadvantage of the Rogers balancer is that the elastomeric retainer band tends to deteriorate after a period of prolonged use. While replacement of the elastomeric retainer band is relatively inexpensive, such replacement is nevertheless time consuming and cumbersome and therefore expensive and undesirable. A still further disadvantage of the Rogers balancer is that at high rotational speeds, the elastomeric retainer band tends to liquify, thus rendering the shaft balancer inoperable and creating an imbalanced condition which necessitates replacement of the balancer and possibly replacement of the unit being balanced.